Injection molding nozzle assemblies having a nozzle body and a separate nozzle tip are well known in the art. The nozzle tip may include a threaded portion to allow for direct coupling to threads on the nozzle body or, alternatively, a removable transfer seal may be provided to secure the tip to the nozzle body. The transfer seal typically includes a threaded portion for mating with threads on the nozzle body.
In addition to securing the nozzle tip to the nozzle body, the transfer seal functions to insulate the hot nozzle tip from the cold mold cavity plate. The nozzle tip is typically comprised of a highly thermally conductive material to facilitate heat transfer from heaters coupled to the nozzle to the melt flowing through the nozzle tip. The transfer seal is typically comprised of a low thermally conductive material, such as titanium, to insulate the nozzle tip from the cold mold cavity plate. The transfer seal further forms a seal with the cavity plate to prevent pressurized melt from escaping into the insulative air space that surrounds the nozzle.
A transfer seal is disclosed in U.S. Pat. No. 5,299,928 to Gellert. The one-piece transfer seal is comprised of a thermally insulative material and includes a portion that is located between the nozzle and the nozzle tip. This one-piece nozzle seal further includes a threaded portion to connect the seal to the nozzle.
As such, a need exists for a transfer seal that provides a good performance over a broader range of applications and that can be replaced in case of partial damage in a more efficient manner.